1. Field of the Invention
The present invention relates to compositions and methods for preventing and treating obesity and its complications. Specifically, the invention relates to methods for preventing and treating obesity using polysaccharides isolated from Ganoderma lucidum as well as methods to prepare the polysaccharides.
2. The Prior Art
Obesity is considered a disease condition associated with numerous health problems and a reduced life expectancy. Growing evidence indicates that obesity is closely linked with chronic, low-grade inflammation which can lead to insulin resistance, type 2 diabetes, fatty liver disease, cardiovascular disease, obstructive sleep apnea, and cancer. The high prevalence of obesity is currently a major threat to public health, with approximately 500 million obese people and 1.4 billion overweight individuals worldwide. Prevention of obesity thus represents a major challenge for modern societies.
A number of interventions, such as calorie restriction, low-carbohydrate diets, and regular exercise, have been used to prevent and treat obesity in the general population. On the other hand, these interventions are difficult to implement on a daily basis and may be associated with low patient compliance when used over a prolonged period of time. Other treatments such as antibiotics and prebiotics are being evaluated for the management of obesity and its related metabolic disorders. For example, antibiotic treatment alters the gut microbiota, reduces blood endotoxemia, and improves glucose tolerance in genetically-modified, obese mice that lack the leptin gene (ob/ob mice) and in mice fed with a high-fat diet (HFD). In addition, prebiotics are non-digestible, fermentable polysaccharides and oligosaccharides, which reduce body weight and exert anti-inflammatory effects, mainly by enhancing the growth of specific beneficial bacteria found in the gut. Prebiotics not only alter the intestinal microbiota but also improve intestinal tight junction integrity and decrease blood endotoxemia caused by bacterial lipopolysaccharides (LPS). Prebiotics may therefore protect animals against obesity-induced inflammation.
The medicinal mushroom Ganoderma lucidum has a long history of use in Asian countries to promote health and longevity. Previous studies have shown that triterpenes and polysaccharides isolated from G. lucidum induce antidiabetic, antihyperlipidemic and antioxidant activities. Yet, it is unclear whether G. lucidum or any of its components may produce beneficial effects on body weight and obesity-related disorders.
In view of the growing incidence of obesity in the human population and with the difficulties observed in prevention and treatment, there is a need for alternative measures to prevent, treat and control this condition. New measures that can be introduced in the diet without necessitating considerable changes in lifestyle and without incurring in toxicity or adverse effects on health are particularly needed.